Alternator rating

[picklebill]

Hi all;

I have a 1982 Sunrader with a 22r engine and manual tranny, and I was wondering if anyone knows what size alternator came with the unit from the factory. Thanks for any info.

Bill

[Dirk]

40, 55, or 60 Amps....

External regulator (Tirrill) = 45 Amps

External regulator (IC) = 40, 55, or 60 Amps

I don't know the visual difference between the Tirill and IC...I think you can tell by the plugs.

Have you tried to check the manufacturer's tag on the alternator?

I plan an upgrade...if you want I can save you my stock alt....free if it matches your application.

Also, there are several places that sell "upgrades." Like Northwest Offroad which carries 90-160 Amp Alternators. (http://www.northwestoffroad.com/parts/alternators.html)

[picklebill]

Hi Dirk - thanks for the info, I guess I forgot to mention that my Alt. has an external IC regulator, so it probably is a 40 amp unit. I will try to see if I can read the tag on my current alternator but it is really hard to get at it. I'm not sure if my alternator is just not up to the task or what, but my group 24 Aux. battery just does't seem to charge all the way up unless I drive on the freeway for at least 4 hours (with the fridge off). I have also noticed that the system is charging at around 13.5 volts which seems low. Since the regulator is solid state, it is not adjustable - I pulled the cover and took a look to make sure. I don't want to buy a new one just to find out it isn't any better. I found an adjustable one by an aftermarket manufacturer but it runs around $75 and I'm not sure it will work with my alternator, and its minimum setting is 14 volts. Do you think 13.5V is high enough to get a full charge into my battery? I would appreciate your advice on this - and thanks for the offer on your old alternator.

Bill

[Shoprat]

Howdy Pickle.

Back in the day when I was a car mechanic, we figuired a charging system should run beyween 13.8 and 14.2 volts at about 1500 r.p.m. An alternator should put out about 40 % in amps of your total battery bank amp rating. For example, your starting battery is 100 amp/hour. Your house battery is 150 amp/hour. These added together equals is 250 amp/hour. 40 % of 250 amps= 100 amps. You need a 100 amp alternator to easily handle the load. Hope this helps.

[Dirk]

I agree with Shoprat....

Also, you might want to figure the rest of the load on you charging system. (Rear Window Defogger...25 amps, High Blower...20 amps, Headlights on low beam...15 amps, high beam...25 amps?, Windshield Wipers...6 amps, Ignition...6 amps, Brake Lights...5 amps, A/C?, stereo system? radio, running lights?, TV?, etc....whatever you might use on the road.)

Heat and is also a factor that affects the alternator's function and life.

Wiring (gauge, length & connections):

I have a 190 AMP alternator in my 1970 1/2 pro-touring Camaro and switched over to a 1/0 gauge wire for the charge and the ground wires. I also took time to add additional grounds to the engine, front clip, and chassis. Then I cleaned and used dielectric gel to coat the almost all of the electrical connections.

I plan to do the same on the Sunrader since many of the connections that I've come across are corroded or use wire nuts. I'll probably redo most of the wiring and do as much soldering as possible.

There are various charts available on the Net to determine what gauge wires you should use based upon the length and load that you are using. http://www.powerstream.com/Wire_Size.htm

If you go with a larger alternator, ask the rep what the at idle output is and be sure to also replace the isolator or isolator/combiner with one rated for your charging system.

Here's a good article: http://superchevy.com/technical/engines_dr...ics/0502sc_alt/

Here's a good FAQ site: http://www.alternatorparts.com/FAQ.htm

Hope that helps.

[picklebill]

Hi guys,

Thanks for the info - I think Shoprat is right - the first thing I need to do is get the charge voltage up to at least 14.0 volts at idle. I'm thinking that after 3 days of camping and the house battery is at about 11.8 VDC, and the starting battery is still at full charge, and I only have to crank the engine for 4 or 5 seconds, the start battery should not be drawing more that a few amps as it still will be essentially at full charge, my house battery will be drawing most of the current. It is a group 24 deep cycle which is rated for around 80 amp-hours (I think) so if the charge rate needs to by about 40% of this rating, my alternator may be able to handle it. Our rig is very basic, so that on the road with the fridge off, during the day, the only draw on the system is probably the ignition and the house battery charge current. And thank you Dirk for the suggestion about increasing the wire guage between the alternator output and the battery - it currently is probably too small. Incidentally, I removed the isolator that was in the rig when we bought it and replaced it with a solenoid, to eliminate the voltage drop across the isolator diodes. I have used this same setup in our last 3 rigs, and it has worked well for me, even though I hear there is some controversy about this approach. Thanks again for the help.

Bill

[Gulfstream Greg]

11.8 volts is really low, that is considered a 35% charge which can actually be damaging to a lead acid battery if left that way for to long. I hope to one day put up some solar panels. I have found that I would have to run the engine for a couple of hours with a 14 volt charge to recover from 11.8 volts to a full charge. High current is good for running high current demand items when the engine is running but I am not sure that all types of batteries will like a high current charge rate as overheating the battery can shorten their life. Also be aware that lead acid batteries produce some serious explosive gasses at high charge and discharge rates and need to be well ventilated. AGM (absorbed glass mat) batteries are a good option as they will take high charge rates and low discharge rates with out damage and with out producing those nasty gasses.

Everyone who I know that has solar have no battery problems and never complain about low batteries. Conservative use of lighting and other appliances are key though to battery capacity. Installation of low current lights made a big difference for me. A second AGM battery will be installed before my next boon dock trip which should also help out greatly. Even though I have said all that I think the high current alternator is a great idea and for me with AGM batteries it would work out almost perfectly. The addition of solar panels would make it all perfect.

[picklebill]

Hi Greg - I know that taking the battery voltage down to 11.8 volts is pushing it, but it never stays there long. I have used this figure for max discharge on my deep cycle house batteries on the last 3 of my RV's and it did not seem to shorten the battery life at all. AGM batteries do look like a better alternative to lead acid but are a little beyond my budget right now. I think my biggest problem right now is the regulator, as 13.5 volts is just not cutting it. Shoprats figures (14 - 14.2) are good, and did remind me that long ago (1960's) when we were intalling 2-way radios in police and fire vehicles, we used the figure of 14.4 vdc as per Motorola specs. I bet the cold cathode flourescent lights you installed have made a big difference in your energy consumption. We mainly use a 15 watt flourescent over the dinette for our main lighting for reading at night and that works OK. I will pursue the after market adjustable regulator to see if it will work with my alternator and take Dirk's suggestion of increased wire size from the alternator to the battery. Thanks for the info.

73's

Bill

[Gulfstream Greg]

Bill

I have an isolator and a switch and voltmeter up front where I can monitor the truck or coach battery. I see 14 + volts all the time to the coach battery and starting battery. One will drop down in voltage while the other stays high so I guess the isolator is doing its job. And yes, radio gear, my reason for the second battery, receive is 1 amp. I actually got the second battery for free. The first though was almost $200 and that is expensive. My converter had burned up my lead acid battery. I have since replaced the converter with a more modern direct replacement. Besides not charging correctly the old one also was a half wave which gave out 4+ volts of ac into the dc circuit. I have graphed the charge rate and now it gives a continuous float charge so I leave the coach connected to shore power at all times.

I think fluorescent lighting is perfect for energy consumption. The cold cathode system takes a lot of fabrication to get installed. As a note one of the drivers for recently burned up, had a melt down two days before a trip. And so I had to purchase another one at a local electronics store at an inflated price. I should get a couple more to keep as a spare.

73's

Greg

[Dirk]

Greg,

What did you use for the direct replacement for the stock converter? I'm thinking of replacing mine soon and was looking for ideas.

Also, I've been doing a bit of research on the whole charging system thing...here's a few interesting links that I have found:

"Mark's Fulltime RV Resource" http://www.ccis.com/home/mnemeth/index.htm

Markl's nice write up on 12 volt systems: http://www.ccis.com/home/mnemeth/12volt/12volt.htm

"Technical Information for Mobile Electronics Installers" http://www.the12volt.com/

This site has a guide to planning a solar sytem for your RV http://www.rvsolarelectric.com/custom.htm

[Shoprat]

Ya know, I just had a thought. These larger alternators suck up a lot of power when charging. These 4 cylinder engines don't need any more power suckers than what is neccessary. I think you would almost be better off if you ran the generator to charge the house battery as you were going down the road. Any thoughts on this?

[Gulfstream Greg]

Greg,

What did you use for the direct replacement for the stock converter? I'm thinking of replacing mine soon and was looking for ideas.

Also, I've been doing a bit of research on the whole charging system thing...here's a few interesting links that I have found:

"Mark's Fulltime RV Resource" http://www.ccis.com/home/mnemeth/index.htm

Markl's nice write up on 12 volt systems: http://www.ccis.com/home/mnemeth/12volt/12volt.htm

"Technical Information for Mobile Electronics Installers" http://www.the12volt.com/

This site has a guide to planning a solar sytem for your RV http://www.rvsolarelectric.com/custom.htm

Here is a page I have been trying to complete for some time, its got the model numbers for both the old and new. One of the best improvements I have done to our rig. http://www.toyotamotorhomes.com/magnetek_6...es_retrofit.htm

[Dirk]

Cool thanks!

[Gulfstream Greg]

Cool thanks!

Bought it thru camping world.

[Shoprat]

Why do I get the feeling I'm being ignored ? Hey Guys, beiing married, my poor ego can't stand this ! Now I'm distressed and it's all you guy'ses fault. Geez, make a brilliant post on the cutting edge of technology any what do you get in return ?

[Gulfstream Greg]

Ya know, I just had a thought. These larger alternators suck up a lot of power when charging. These 4 cylinder engines don't need any more power suckers than what is necessary. I think you would almost be better off if you ran the generator to charge the house battery as you were going down the road. Any thoughts on this?

I know there are some that run their gens so they can run the coach a/c. If you did run it for charging what actually would be doing the charging is your converter. The converter might actually have a slower charge rate than your alternator regulator charging system. As far as the engine and power I don't think you would notice a difference from the stock. The battery will only take a high current charge for a short while then taper off as it gets fuller. Where you would notice it is if you had every 12 volt accessory on at the same time, like 12 volt refer, high powered driving lights etc. That would be a constant demand and a constant load and would would pull some horse power.

[nolan]

Your right Greg, Thats where I see the difference, I run a 130 amp alternator on my Chinook, never noticed any difference in power driving, but when the AC, lights, driving lights, wipers, heater, ect. are in use I never see the amp gauge move as it does in my other one as accessories are turned on and off.

Thats on my to do upgrade list for Blew in the near future, MO Power!!!